Portable devices, such as handheld communications devices, such as car keys (including keys with fobs), cellular telephones, remote controls, and the like, are often misplaced. A device may be left in an unusual place or be covered by other objects, making it difficult to locate the device when the user wants to retrieve it. Many scenarios include a human attempting to locate a source of an audible signal. For example, locating misplaced portable devices, finding an exit in a smoke-filled building, guiding rescuers to an injured person, assisting in directing a visually impaired individual to find, for example, a direction in which to proceed to cross a street or find an exit, or any combination of these instances are cases where people use directional locations to a source of an audible signal.
Although various techniques are used to create audible signals as notifications, such as fire alarms, the frequency characteristics of these notification tones are often selected to most efficiently alert a human user, and not to aid in location of the device. Assisting a user in locating a source of audible signals is improved by generating audible signals that efficiently interact with physical human hearing mechanisms and psychoacoustic phenomena.